1. Field of the Invention
The present invention relates generally to calendars, especially to a single axis rotatable disc calendar, and to methods of calculating time periods and future dates based on current or past events. More particularly, the invention relates to calculators for determining fertility timing, testing and treatment time periods and future event dates.
2. Description of the Prior Art
Many professions require the calculation of time periods in days, weeks and months, either forwards or backwards, for purposes of establishing a date or dates at some increment of time from a given start date, or from a particular event. Such calculations often require knowing the day of the week a calculated date falls on, or planning a schedule of events so that particular events fall on certain days of the week, or to avoid weekends. These calculations are often critical in terms of deadlines imposed by laws, rules or contracts. These calculations are complicated when time periods run for several months, which have different numbers of days, and especially for time periods running over February in a leap year. Professions requiring these types of calculations include law, banking, insurance, construction and medicine. In particular, the field of human fertility medicine involves many complex time period calculations.
Human fertility, infertility, and contraception evaluations are characterized by a large number of basic tests, the majority of which require accurate timing relative to the female menstrual cycle or ovulation cycle. Many contraceptive methods, fertility therapies, or infertility treatments are also dependent on menstrual cycle or ovulation timing.
Human fertility physiology is unique among the mammals, especially regarding the female system. The male system is a relatively simple design consisting of a continuous “conveyor belt” sperm production factory under the control of a non-cyclic hormone, testosterone, itself under the control of a non-cyclic central axis of lutenizing hormone (LH), follicular stimulating hormone (FSH), and GnRH hormones. In contrast, the female system is much more complex, consisting primarily of interdependent physiologic cycles designed to release a fertilizable egg cell at an optimal point in time to maximize successful reproductive potential. This system is characterized by endocrine negative and positive feedback cycles utilizing changes in the concentrations of estrogen and progesterone under the control of cyclic LH, FSH, and GnRH central axis hormones. The final product of these cyclic control systems is the female menstrual cycle. Hormone levels, anatomic changes, ovulation (and thus fertile periods), and embryo implantation patterns are integral parts of the menstrual cycle, and occur at specified points or ranges within the cycle. Pathologic alterations in the female reproductive systems also follow repeated patterns in the menstrual cycle, including hormone imbalances, abnormal (or absent) ovulation, uterine lining preparation problems, or embryo implantation difficulties. Because the normal and the pathologic components of the menstrual cycle occur in a predictable, repetitive temporal pattern, they can be described by algorithms, with each component tied to a relatively fixed landmark event in the cycle.
Several devices are known for calculating a variety of time periods and timing various things. U.S. Pat. No. 4,751,373 to Ivey discloses a time period calculator in which a wheel with 365 divisions for days of the year is further divided into weeks and months. A cursor is provided to accommodate a leap year.
U.S. Pat. No. 5,313,723 to Cregg discloses a perpetual calendar comprising two discs. One disc has a window with adjacent marks indicating the days of the week, and other marks indicating months and years. The second disc contains year tables and day grids. The user adjusts the two wheels to show the monthly calendar for any month of any year, including leap years.
Gestational calculating wheels are simple calculating devices used to determine the gestation age of a pregnancy for any calendar date, and to determine landmark events of a pregnancy such as the expected delivery date. These circular rotating scale calculators are made in a large variety of design formats. The basic design consists of a calendar date scale of one year length wrapped once around a circular scale containing 365 days. A single independently rotating scale attached to the center pin contains gestational week markings, along with other printed pregnancy information, tests, and treatments that are dependent upon gestational age. The gestational age circular scale always contains a label for the first day of the last menstrual period (LMP), and some have a label for ovulation or conception day. These gestational calculating wheels are used only for displaying pregnancy related information, not for fertility test or treatment information, and they have no markings for cycle days.
A Depo-Provera calculating wheel is often distributed to medical personnel who dispense the contraceptive drug Depo-Provera, which is administered as an injection given once every 12 weeks. This device is similar to the gestational calculating wheel, using the same calendar date scale, but its single independently rotating medication day wheel ranges over the entire circumference instead of a nine-month circumference. The medication day wheel contains four approximately equal spaced markings (12 weeks apart) indicating the times to schedule Depo-Provera injections during the year.
U.S. Pat. No. 4,092,521 to Weisshaar discloses a circular scale coaxial device made of 3 or 4 independently rotating scales that determine the fertile time periods and the “sterile” time periods during a menstrual cycle. The first disk displays a fixed 31-day calendar month wrapped around the entire circumference of a circular scale. The other disks display 31 cycle days, fertility periods, and sterility periods. An optional fourth disk is used to display a reverse cycle backward from the next following menstrual cycle. No labels for fertility tests or treatments are included.
U.S. Pat. No. 4,465,077 to Schneider discloses an electronic computer with keypad data entry which stores information from a patient's medical history, including past menstrual cycle dates, basal body temperature (BBT) charts, gynecologic disorders, and ovulation prediction indicators. It then statistically calculates the patient's fertility status and estimated chance of achieving pregnancy. This device is not used to time specific fertility tests or treatments.
U.S. Pat. No. 4,625,099 to Freedom discloses a circular scale coaxial device made of a 365-day calendar date scale and an independently rotating cycle day scale. The entire calendar year is wrapped once around the calendar date scale. An overlying cycle day scale is also divided into 365 equal days, with several menstrual cycles displayed as marked domains separated from each other by small “spacer” segments. The cycle domains have as few as 23 days or as many as 35 consecutive days each, with the remaining cycle domains having an incrementally larger number of days between these two extremes. Within each cycle domain, the cycle days are numbered consecutively from the first day of the last menstrual period. The only other labeled indicator marks “fertile” days for two days prior and two days after expected ovulation, and alerts the user to the optimum fertility period of the cycle. Presumably, the user will ignore all the other cycle domains and use only the one that contains her average cycle length.
U.S. Pat. No. 4,737,619 to Freedom discloses the addition of “non-fertility” labels to the device described above, and extends the range of cycle lengths in domains from 20 days to 35 days, instead of 23 days to 35 days.
U.S. Pat. No. 4,752,880 to Aeschlimann discloses an electronic calculator designed to store the patient's basal body temperature (BBT) data during a menstrual cycle. The calculator contains counters which allow entry of BBT data only at 24-hour intervals in order to improve accuracy.
U.S. Pat. No. 5,310,994 to Thabet discloses a non-complex circular scale device containing a calendar scale displaying the days of the month, and an independently rotating circular scale displaying the average number of days in the user's menstrual cycle. The simple design is intended for use in Third World countries, to identify fertile and non-fertile times of the menstrual cycle.
U.S. Design Pat. No. D389,587 to Porrazzo discloses an ornamental design for a slide device to display fertile times of the menstrual cycle.
U.S. Pat. No. 3,964,674 to Van der Gaast discloses a circular scale coaxial device containing a basic plate with “longest period” scale printed as a portion of the circumference, and two independently rotating middle and top plates onto which “shortest period” and “LMP day of month” pointers are printed. Data windows cut into the top plate reveal the first and last days of the fertile period for that cycle. Operation of this device is complicated due to confusing labeling and the use of three sets of date windows to be used with three sets of calendar months.
U.S. Pat. No. 4,350,878 to Schwartz discloses a circular scale coaxial device containing a base plate with menstrual period—basal temperature—ovulation scale printed on a portion of the circumference, a middle plate with a reversed single cycle day scale on a portion of its circumference, and a top plate circumferentially divided into two generic months, a 30-day and a 31-day, around the entire circumference. The middle plate is transparent to allow visualization of the alignment with the other plates. An optional second transparent plate can be added between the base plate and middle plate, upon which another ovulation range marked is printed to extend the use of the calculator for users with variable cycle lengths. This device is severely limited by its “two generic months” for calendar date application because it does not allow for 31 day-to-31 day transitions or for February/leap February transitions. The LMP and ovulation range markers are also severely limited by their fixed distance because they are both printed on the same scale and plate, although the optional second ovulation plate can partially overcome this problem.
U.S. Pat. No. 4,752,674 to Rosenwaks discloses a circular and spiral scale coaxial device containing a base plate with its circumference evenly divided into a 28-day scale, a transparent middle plate containing a spiral scale with over 4 turns upon which 3 generic months are printed (30-day then 31-day then 30-day), and a transparent top plate containing a 14-day “Donor” scale on half of the circumference along with rectangular arc data windows for reading results on the base plate scales. An In Vitro Fertilization egg donor cycle hCG ovulation trigger injection day can be rotated on the top plate to correspond with the recipient's LH surge cycle day, to determine the optimal day of subsequent embryo transfer into the recipient's uterus. This device also has a severely restricted calendar day scale that cannot accommodate a 31 day-to-31 day transition or February/leap February transition.
None of the prior art devices provide a simple, accurate, easy to read device for calculating time periods and future dates, which takes into account leap years and the varying month-to-month transitions. In particular, none of the prior art devices provides a device for easily and accurately determining and displaying the calendar date, weekday, and cycle day of nearly all fertility and family planning tests and therapies, which takes into account leap years and the varying month-to-month transitions. It is an object of the instant invention to provide such devices.